Dishwasher Air Gap: What Is It and Why It Matters

Have you ever noticed a cylinder-shaped object sitting on your kitchen countertop and wondered what it is? It’s known as an air gap and is a necessary component to ensure your dishwasher drains effectively. In some areas, an air gap is even a mandated part of the plumbing code, so it’s essential to meet all necessary legal and insurance requirements. 

Although there are some alternatives to using an air gap, they’re one of the simplest and most effective solutions to ensure proper drainage without backflow. Let’s take a closer look at how they work, why they’re important, and what alternatives are available. 

How your dishwasher air gap works

A dishwasher air gap is designed to prevent dirty water from flowing back into your dishwasher, but how does it work? The process is actually pretty simple!

• The dishwasher drain hose is connected to a small plastic cylinder on your countertop. 
• Inside the air gap cylinder, there is another cylinder that lets air in. This breaks the suction and prevents the dirty water from flowing back in. 
• The dirty water is then able to flow into your sink drain as normal, without the risk of siphoning or backflow. 

Why your dishwasher air gap matters

If you’re planning to install a new dishwasher you might be wondering how much an air gap actually matters. Although there are alternatives, an air gap is a great, cost-effective way of ensuring your dishwasher operates optimally. 

Stops contamination

The air gap prevents dirty water from flowing back into the dishwasher. This ensures your dishes are fresh and clean and not contaminated with chemicals and dirty food particles. 

Aids drainage

An air gap helps your dishwasher get a complete drain. This means that water is not left standing in the bottom of your dishwasher, which can lead to mildew growth and bad smells. 

Ensures code compliance

Many places in the US require an air gap to be installed to ensure your dishwasher is up to code. Failure to comply with the code can lead to fines or can void your insurance if there is a leak. 

Easy to spot blockages

Another advantage of an air gap is that it works like an early warning system when there’s a blockage. If you notice water starting to leak from the air gap, it is an indication there is a problem elsewhere in your dishwasher’s wastewater system, such as a clogged filter or kinked hose. 

Alternatives to a dishwasher air gap

While air gaps are a common and highly effective solution for backflow, there are some other methods that you can use that achieve the same effect. However, make sure you check your local plumbing codes before you decide on a backflow prevention method so you can ensure compliance. 

High loop method

This is the most straightforward alternative to an air gap, although it is less effective. Simply ensure that the dishwasher drainage hose is looped up as high as possible under the kitchen counter before joining the sink drain. The elevation reduces the risk of siphoning and makes it harder for dirty water to flow back into the dishwasher. This method may not be compliant with all plumbing codes.

Standpipe

This method is ideal for dishwashers that have a drainage system that is separate from the kitchen sink. The drainage hose is inserted into a vertical pipe, allowing efficient drainage without backflow. This method is code-compliant but only suitable for certain dishwasher models and kitchen setups. 

Check valve

An alternative to the air gap is a check valve, which is a valve designed to prevent water from flowing back into the dishwasher. Combined with the high loop method, this is an effective way of preventing backflow. The one issue is that the valve may malfunction over time due to wear and tear. 

Common issues with dishwasher air gaps

Although dishwasher air gaps are simple and effective at preventing backflow, they can encounter issues. These include:

• Clogs: Sometimes food debris and detergent buildup can occur inside the air gap cylinder, which prevents proper drainage. This can lead to leaks on your countertop and backflow into your dishwasher. 
• Strange noises: If your air gap is clogged or incorrectly installed, it can start to make strange gurgling noises. This is due to air being forced through the cylinder. 
• Wear and tear: Over time, the plastic parts of your air gap can degrade and become cracked or discolored. Once damaged, the air gap won’t function as effectively, which can lead to leaks and backflow problems. 
• Unpleasant odors: If food debris builds up inside the air gap, it can start to decay and smell bad. Air gaps are also prone to growing mildew and bacteria, which can result in musty, unpleasant smells. 

Maintaining your dishwasher air gap

To keep your air gap functioning optimally and prevent any common issues, regular maintenance is recommended. 

Clean it regularly

The best way to prevent clogs is to keep the air gap clean. Every few weeks, remove the cover of the air gap and clean the inside thoroughly with a small brush or pipe cleaner, then rinse the entire thing thoroughly. 

Deal with any leaks immediately

A leak is usually a sign of a clog or blockage, so make sure you always investigate if you notice water pooling around the air gap. 

Replace damaged parts

Any plastic part can degrade over time, and air gaps are no exception. If your air gap is getting old and you notice cracks or other signs of degradation, it’s best to replace the parts before the entire unit fails. 

Deep clean occasionally

Although a regular clean of food debris can be done with just a brush and warm water, occasional deep cleans are needed to remove soap scum. Remove the unit and soak it in white vinegar, before thoroughly scrubbing away the debris.